1. Field of the Invention
The present invention relates to a scroll fluid machine which performs compression, expansion, and pressure feeding, specifically a scroll fluid machine of which the outermost wrap of either of the stationary or revolving scroll which is larger in diameter is formed into an annular shape to form the outermost wall of an enclosing body for taking in fluid to be compressed.
2. Description of the Related Art
A scroll fluid machine having a stationary scroll and a revolving scroll is well known. Art disclosed in Published Unexamined Patent Application No. Hei-7-208353 is one. According to this art, as shown in FIG. 12, a stationary scroll 106 has a space 108 and a wrap 100, an annular groove 122 is formed on the mating face 121 of the stationary scroll 106, an elastic element 127 and a seal element 123 are arranged in the annular groove 122, and a revolving scroll 107 revolves while its mirror surface slides on the seal element 123.
The portion 121B of the mating face 121 is essentially not needed for taking in and compressing fluid. The mirror surface of the revolving scroll 107 is required to be extended over the portion 121B of the mating face 121, which leads to a larger diameter of the revolving scroll. The width of the mating face 121 of the stationary scroll is enough as long as the annular groove 122 can be formed with narrow rims on both sides of the annular groove 122 remaining.
According to the prior art, therefore, there remains an essentially not necessary, not slimmed portion, which hinders downsizing of the scroll fluid machine.
On the other hand, in order to achieve a high compression ratio, or a high pressure ratio in the case of a scroll compressor, the number of turns of scroll wraps is to be increased, and to shorten the time for evacuating a vessel in the case of a scroll vacuum pump, the suction volume of fluid is to be increased. To achieve high compression ratio or to shorten the time for evacuation, the revolving radius of the revolving scroll is required to be increased, leading to enlarged outer dimensions of the scroll fluid machine.
However, the space 108 is to be expanded in order to meet the requirements for using the prior art, which leads to an increased revolving radius of the revolving scroll and increased friction of the seal element 123, for the seal element 123 is to be lengthened owing to increased diameter of the annular groove. Further, for achieving a high compression ratio, the arrangement of a seal element between each of the top faces of the wraps and each of the mating sliding surfaces is necessary to prevent the leakage of compressed fluid from a compression chamber higher in pressure to that lower in pressure in the process of compression, the chambers being formed by the wraps of the revolving scroll and stationary scroll. The lengths of these seal elements are increased as the dimensions of the scroll fluid machine increase, and the friction by the seal elements also increases.
The present invention is done in the light of problems cited above. An object of the invention is to provide a scroll fluid machine capable of being small sized.
Another object of the invention is to provide a scroll fluid machine capable of achieving high compression ratio or high pressure ratio without enlarging the outer dimensions of the scroll machine.
A still further object of the invention is to provide a scroll fluid machine capable of preventing the increase of load by friction when the achievement of a high compression ratio is intended.
A yet further object of the invention is to provide a scroll fluid machine capable of saving the usage of the materials of scrolls, seal elements, etc.
The present invention is a scroll fluid machine having a stationary scroll and a revolving scroll, each scroll having a spiral scroll wrap spiraling from the center side to the outer side, one of the scrolls having an annular, outermost wrap of which the radius is larger than that at the outer end of the spiral wrap of the other scroll. The annular, outermost wrap is the outermost wall, and the scrolls are assembled so that the wrap of the other scroll is disposed in the inner side of the of the said one of the scrolls.
According to the invention, either one of the stationary or revolving scroll, each scroll having a spiral scroll wrap spiraling from the center side to the outer side, is provided with an annular, outermost wrap. The radius of the outermost wrap is larger than that at the outer end of the spiral wrap of the other scroll, and the outermost wrap forms the outermost wall of the said one of the scrolls, so the outermost wall has no excess width of rims as is the case with the prior art. The one and the other scrolls are assembled so that the wrap of the said other scroll is disposed in the inner side of the wrap of the said one of the scrolls. Therefore, the scroll mechanism becomes small sized, and the downsizing of the scroll fluid machine is achieved.
Accordingly, the light weight of the constituent elements of the scroll fluid machine is achieved, the load for driving the scroll mechanism is lightened, and the power for driving the scroll fluid mechanism is reduced.
Thus, a higher compression ratio or a higher pressure ratio is achieved with the same dimensions of the scroll fluid machine as in the prior art.
Also, the present invention is a scroll fluid machine having a stationary scroll and a revolving scroll, each scroll having a spiral scroll lap spiraling from the center side to the outer side, one of the scrolls having an annular, outermost wrap with the diameter larger than the outer end of the spiral wrap of the other scroll. The annular outermost wrap is the outermost wall, and the scrolls are assembled so that the wrap of the other scroll is disposed in the inner side the one of the scrolls. A seal element for sliding surface sealing which contacts with the mating sliding surface is provided on the outermost wrap.
According to the invention cited above, each of the seal elements provided on the wraps of the stationary and revolving scrolls slides on each mating sliding surface to keep the chambers formed toward both sides of the wrap sealed, so the leakage of the compressed fluid from a compression chamber higher in pressure to that lower in pressure is prevented, and high compression ratio, or high pressure ratio, can be achieved.
According to this second invention, as in the first invention, either one of the stationary or revolving scroll, each scroll having a spiral scroll wrap spiraling from the center side to the outer side, is provided with an annular, outermost wrap. The radius of the outermost wrap is larger than that at the outer end of the spiral wrap of the other scroll, and the outermost wrap forms the outermost wall of the said one of the scrolls, so the outermost wall has no excess width of rims as is the case with the prior art. The one and the other scrolls are assembled so that the wrap of the said other scroll is disposed in the inner side of the wrap of the said one of the scrolls. Therefore, the scroll mechanism becomes small sized, and the downsizing of the scroll fluid machine is achieved.
Further, as a seal element for sliding surface sealing which contacts with the mating sliding surface is provided on the outermost wrap, the seal element for sliding surface sealing on the outermost wrap achieves the role of sealing dust while at the same time achieving the sealing of fluid without providing an extra dust seal still outside of the outermost wrap.
Accordingly, the light weight of the constituent elements of the scroll fluid machine is achieved, the load for driving the scroll mechanism is lightened, and the power for driving the scroll fluid mechanism is reduced.
Thus, a higher compression ratio or a higher pressure ratio is achieved with the same dimensions of the scroll fluid machine of the prior art.
As the outermost wrap achieves the role of the outermost wall, it is required to use a dust seal having superior resistance to wear, but a seal with superior resistance to high temperature and high pressure is not required.
It is also an effective means of the present invention to compose the outer side end of the spiral wrap of the said one of the scrolls so that it connects with the outermost wrap at a connecting part formed at the partway of the of the outermost. A chip seal is provided on the wrap of the said one of the scrolls from the center side end till the connecting part, and a dust seal is provided on the outermost wrap, the dust seal working as a slide surface seal element of the outermost wrap.
The slide surface seal element is required to be a dust seal having superior resistance to wear but is not required to be a seal with superior resistance to high temperature and high pressure.
It is also an effective means of the above-cited second invention to compose a scroll fluid machine so that the outermost wall is a first outer wall which has an outer side end part on a scroll wrap of the said one of the scrolls and a beginning part at a certain length toward the center, and a second outer wall which extends in the direction of the circumference from the outer side end to form a fluid taking-in chamber for taking in fluid and joins with the beginning part. A chip seal is provided on the wrap of the said one of the scrolls from the center side till the outer side end, and a dust seal is provided on the second outer wall, the dust seal and the chip seal working as sliding surface seal element.
According to the technical means cited above, it is. possible to select a dust seal having superior resistance to wear for the second outer wall which confines the take-in chamber for taking in fluid from outside, and to select a chip seal having superior resistance to high temperature and pressure for the first outer wall of which the temperature becomes higher than that of the second outer wall. Therefore, excessive quality of the seal material is evaded, which is economical and contributes to the development of industry.
As the first outer wall is the extension of the spiral wrap, the same chip seal is used for the first outer wall and the spiral wrap, and the assembling process is simplified.
It is effective to compose the present invention so that the outer side end of the spiral wrap of the said one of the scrolls connects with the outermost wrap at a connecting part formed at the partway of the of the outermost wrap, and a chip seal is provided on the wrap of the said one of the scrolls from the center side end all over the outermost wrap, the chip seal working as a slide surface seal element of the outermost wrap.
According to the technical art cited above, as the same chip seal is provided on the spiral wrap and outermost wrap, the groove shape is the same on the spiral wrap and on the outermost wrap, which simplifies the machining process of the grooves.
It is also an effective means of the second invention that the chip seal is shaped so that the thickness i.e., the dimension in the direction of the depth of the groove, becomes greater from the outer side toward the center side of the scroll.
The thermal expansion of the chip seal is greater in the center side because of higher temperature, and the contact pressure of the chip seal to the sliding surface increases, leading to increased wear. By increasing the thickness of the chip seal toward the center side, its longevity is increased.
It is effective to compose the present invention so that a chip seal, on the outer side of which is provided a groove wall seal element exerting elastic force between the chip seal and the outer side wall of the chip seal groove formed on the scroll wrap, is disposed in the chip seal groove.
As the pressure in an enclosed space formed toward the outer side of a wrap is lower than that formed toward the inner side of the wrap, the chip seal is pressed outward. By providing the groove wall seal element between the chip seal and the outer side wall of the chip seal groove, even if a gap develops between the groove wall and the side face of the chip seal in the higher pressure side, and between the lower face of the chip seal and the bottom face of the groove, a leak of the fluid is prevented by the groove wall seal element.